The Images page shows what images and architectures have been selected and
downloaded. By default, MAAS will automatically grab the most recent Ubuntu LTS
releases (and amd64 architecture). Below, two additional releases have been
selected:

In the top-right corner there is a toggle switch for the automatic syncing of
images. It is highly recommended to keep this enabled.

Note: Image sync occurs hourly and the availability of new images is influenced by the image stream MAAS is configured to use. See Boot image sources.

To change the selections select any other images (by choosing 'Release' and
'Architecture'), and click the 'Save selection' button to initiate the import.
Existing images will be shown in addition to the newly selected ones. The
latter will have their status updated as the import is processed:

To remove an image, simply unselect it and click 'Save selection'.

Other images

It is also possible to import and provision images other than Ubuntu. Images
supported and provided by MAAS will appear beneath the 'Other Images' section.
Currently, images for both CentOS 6.6 and CentOS 7.0 are available and these
can be imported and used just like the Ubuntu images above.

Using a local mirror

Optionally, a local mirror can be set up as the boot source. MAAS will then use
it instead of the standard internet-based server. This will reduce the time
required to complete the image import step significantly. See
Local image mirror for instructions on doing this.